Covalent Hybrid Elastomers Based on Anisotropic Magnetic Nanoparticles and Elastic Polymers

Particle-filled elastomers are ubiquitous composite materials with applications ranging from durable materials, such as tires, to smart actuators and sensor materials. By employing magnetic nanoparticles as multifunctional, inorganic cross-linkers, PDMS-based hybrid elastomers with a novel unique architecture and a defined type of particle-matrix interaction are obtained—a direct covalent coupling between magnetic and elastic properties. The resulting particle-cross-linked elastomers possess application potential due to their defined magnetomechanical coupling and their large extensibility. As the filler phase, spindle-shaped hematite nanoparticles with a silica shell are used, and the swelling, thermal, magnetic, and mechanical properties of the resulting particle-cross-linked elastomers are systematically evaluated and compared to the properties of analogous yet conventionally cross-linked particle-filled elastomers of a similar composition. Some unique features are found for the hybrid elastomers, such as a large strain at break of up to εB ≈ 1700%, that are attributed to the exceptional architecture, combining a well-integrated network of long polymer chains that are interconnected by network nodes with a high cross-linker functionality formed by the anisotropic magnetic nanoparticles.